how much the dept is is not the main issue in this. The USA has the huge amount of dept more than everybody in the world does, but they are in a better shape than Greece, Italy and Spain. this is because basically the government can make money that makes the USA able to pay its dept. Unlike the other 3 countries I've mentioned. They don't make enough money that they can handle their dept. But overall, the western countries especially European countries suck. On the other hand, eastern countries (China, Russia and S.Korea)are doing way better. does this tell you something about who will be more powerful in the world in the near future?

So, why is Spain being picked on?
Also note that debt overall for the Euro area is at a still-manageable 90% of GDP: get your act together and accept the common fiscal consequences of the EU and, I promise, the pain will go away immediately.

The reason that Japan is not "on the firing" line are none of the reasons offered by the Economist. It's because Japan is sovereign in their own currency, and all their debt is in local currency. They create money. No outside creditor will ever force them to default. Full stop. The same holds true for those countries soveriegn in their currency and whose debts are in local currency, such as the US, UK, Australia, Canada - they cannot involuntarily default.

The reason Greece, Ireland, Portugal, and other Eurozone countries are at risk of default is that they must find euros to pay their debts - they cannot create euros.

As shown here, sovereign debt for the world's developed economies is anticipated to rise from 91 percent of GDP at the end of 2009 to 110 percent in 2015, an increase of 37 percentage points since the beginning of the Great Recession:

With GDP growth rates shrinking or becoming negative, the GDP-to-debt levels for many Eurozone nations will reach levels that are unsustainable, forcing nations like Greece, Italy and Spain to consider default.

@AtlasBridge - the chart above is specifically Government debt, looking at your numbers they include all debt - companies, banks and households as well as governments. The Economist has an interactive chart a while back that showed the breakdown - I'll post a link when I find it

Indeed there is no simple gauge to explain investor sentiment when one goes for a general comparative analysis.
On assessing case by case, i.e. each country on its own strengths and weaknesses then a sharpened picture emerges.
It still does not explain every single move by the markets but their judgment starts to make a great deal more sense.

Having arrived at such a critical crossroads - the Eurozone has gone on to a worse one everytime - key questions need to be addressed and settled before long. They were always there and known to most but this winding path had to be footed first(?).

Going by official speech the break-up of the Euro is not on the cards.
How much longer can politicians hold off the markets when under current assumptions nearly all has been said and done?
The blame game is long up. It never paid any dividends anyway.
That brings us back to square one. To how a monetary union of 17 diverse cultures and economies (there being overlapping between them doubtless) can be made to work reliably.
Economic efficiency being largely divergent by groups of countries underscores the fact, by contrast, that financial intertwinning has advanced greatly.
This is why default by a single member poses a real threat to all.
To the Eurozone, the larger EU and the wider world to a limited extent.

There was never a time when the adage sounded truer:
United we (Eurozone) stand, divided we (Eurozone) fall.

A glance at the chart suggests others should have been 'assaulted' first. They haven't.
A deeper look reveals why they haven't.